Jefferson County, Colorado
A county in Colorado, ranked 4 of 64 by population.
CountyFIPS 08059
- Population
- 580,451
- -2,680 (-0.5%) since 2020
- Land area
- 764.4
- square miles. A further 1.2% of the total area is water
- Population density
- 759
- people per square mile, computed rather than published
- County seat
- Golden
- Seat of county government.
- Established
- 1861
- 164 years ago
- Largest city
- Lakewood city
- Population 156,927.
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.
Satellite view
Aerial imagery of Jefferson County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.
Where Jefferson County ranks
Position among the 64 counties of Colorado, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.
| Measure | Value | In Colorado | Nationally |
|---|---|---|---|
| Population | 580,451 | 4th of 64 | 124th of 3,144 |
| Land area | 764.4 sq mi | 50th of 64 | 1,141st of 3,144 |
| Population density | 759 per sq mi | 4th of 64 | 201st of 3,144 |
| Median household income | $110,656 | 4th of 64 | 93rd of 3,143 |
Full data for Jefferson County
| Measure | Value | Source and vintage |
|---|---|---|
| Population | 580,451 | Vintage 2025 Population Estimates |
| Population in 2020 | 583,131 | Vintage 2025 Population Estimates |
| 2020 estimates base? | 582,929 | Vintage 2025 Population Estimates |
| Land area | 764.4 sq mi | 2025 Gazetteer Files |
| Water area | 9.6 sq mi | 2025 Gazetteer Files |
| Total area | 774.1 sq mi | 2025 Gazetteer Files |
| Population density? | 759 per sq mi | Computed: Vintage 2025 estimates divided by 2025 Gazetteer land area |
| Median household income | $110,656 | American Community Survey 2020-2024 5-Year Estimates |
| Median home value | $637,600 | American Community Survey 2020-2024 5-Year Estimates |
| Median age | 40.5 | American Community Survey 2020-2024 5-Year Estimates |
| Households | 241,735 | American Community Survey 2020-2024 5-Year Estimates |
| Housing units | 253,574 | American Community Survey 2020-2024 5-Year Estimates |
Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.
How the population changed
The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:
- Births minus deaths
- +795
- 5,667 births, 4,872 deaths
- Net migration
- -748
- More people moved out than moved in.
Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.
The 10 areas bordering Jefferson County
Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.
| Bordering area | State | Shared border | Population |
|---|---|---|---|
| Douglas County | Colorado | 46 mi | 399,396 |
| Park County | Colorado | 34 mi | 18,314 |
| Denver County | Colorado | 33 mi | 740,613 |
| Broomfield County | Colorado | 15 mi | 79,174 |
| Boulder County | Colorado | 13 mi | 328,560 |
| Clear Creek County | Colorado | 12 mi | 8,994 |
| Gilpin County | Colorado | 12 mi | 6,073 |
| Adams County | Colorado | 8.5 mi | 554,668 |
| Arapahoe County | Colorado | 4.5 mi | 673,820 |
| Teller County | Colorado | 266 ft | 24,756 |
Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.
Side by side
All 64 counties of Colorado
Open the interactive Colorado county map, or jump straight to any of them.
- Adams County
- Alamosa County
- Arapahoe County
- Archuleta County
- Baca County
- Bent County
- Boulder County
- Broomfield County
- Chaffee County
- Cheyenne County
- Clear Creek County
- Conejos County
- Costilla County
- Crowley County
- Custer County
- Delta County
- Denver County
- Dolores County
- Douglas County
- Eagle County
- El Paso County
- Elbert County
- Fremont County
- Garfield County
- Gilpin County
- Grand County
- Gunnison County
- Hinsdale County
- Huerfano County
- Jackson County
- Jefferson County
- Kiowa County
- Kit Carson County
- La Plata County
- Lake County
- Larimer County
- Las Animas County
- Lincoln County
- Logan County
- Mesa County
- Mineral County
- Moffat County
- Montezuma County
- Montrose County
- Morgan County
- Otero County
- Ouray County
- Park County
- Phillips County
- Pitkin County
- Prowers County
- Pueblo County
- Rio Blanco County
- Rio Grande County
- Routt County
- Saguache County
- San Juan County
- San Miguel County
- Sedgwick County
- Summit County
- Teller County
- Washington County
- Weld County
- Yuma County
Data on this page last rebuilt 30 August 2026. How these figures are produced.